Article abrading apparatus

ABSTRACT

The disclosure is an article abrading apparatus having an article carrier belt and arms including abrading members moving across the belt with abrasive reciprocating motion. Abrasive contact with articles of flat and triangular cross sectional shapes is provided by a pivotally hinged arrangement of abrading members which are positioned by movable roller bars sensing the surface tilt of contour of an article passing beneath.

1973 T. GUTBERREZ ET AL 3,734,700

ARTICLE ABRADING APPARATUS Filed May 10, 1971 3 Sheets-Sheet 1 INVENTORSTHOMAS GUTI ERREZ WALLACE AMARAL.

PATENT AGENT May 22, 1973 T, GU-HERREZ ET AL 3,734,70Q

ARTICLE ABRADING APPARATUS Filed May 10, 1971 3 Sheets-Sheet 2 INVENTORZTHOMAS GUTIERREZ WALLACE AMARAL 4 /%//m 1;; f%// PATENT AGENT O 0% @o WN@N o mm wm E m Filed May 10, 1071 3 Sheets-Sheet m m $1 1' L0 \X Q on G3N \9 m N O. a N g m l 1 N q r 6) no r -&

INVENTORS THOMAS GUTIERREZ WALLACE AMARAL BY 1 l ,V I

PATENT AGENT United States Patent Oflice 3,734,700 Patented May 22, 19733,734,700 ARTICLE ABRADIN G APPARATUS Thomas Gutierrez, 395 N. MadisonSt. 95050, and Wallace Amaral, 2547 Amethyst 95051, both of Santa Clara,Calif.

. Filed May 10, 1971, Ser. No. 141,761

Int. Cl. B24b 7/12 US. Cl. 5161 10 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION In printed circuit technology it is highlydesirable to obtain circuit boards with smooth surfaces. Drilling holesthrough the boards for mounting components usually produces smallsurface burrs which interfere with subsequent circuit board platingoperations. Hence, it is necessary in these cases to de-burr the circuitboards in at least one stage of circuit board preparation.

Some polishing, de-burring and similar surface treatment machines havepreviously used complex mechanisms to achieve the desired surfaceeffect. This is especially true where orbital abrasive motion wasapplied to a surface. In order to treat the entire surface such machinesmust include means for moving the abrasive orbit only after suflicienttreatment is applied to a certain location. One method of achieving thisis by a complex camming arrangement.

On the other hand, simple machines such as rotating roller brushesusually require large abrasive surfaces, any part of which is in contactwith the treated material only a small portion of the time. Rollerbrushes have the disadvantage of producing a somewhat uneven result,especially if some single part of the brush loses its abrasive quality.

The object of the present invention is to provide a simple, low cost,highly efficient abrading apparatus for generally fiat articles.

Another object is to provide an abrading apparatus for articles having atriangular cross section.

A further object is to provide an apparatus for abrading articles ofboth very small and large size.

Still a further object is to provide an article abrading apparatus whoseabrading surfaces can be quickly and cheaply replaced.

SUMMARY OF THE INVENTION The above objects are achieved with anapparatus havmg liftable, tiltable abrasion arms mounted for transversemotion facing an article carrier belt or web. The arms include generallyfiat sliding members extending over and across the article belt with anabrading member facing the belt and drive members from which the slidingmembers are suspended from a single pivot.

The drive members of the several arms are arranged in two sets, eachrotatably cantilevered from an end and connected to a motive means oneither one of the opposite sides of the belt. The pivot for each slidingmember is slightly ofr center so that each sliding member will tilt witha see-saw motion when it is pulled across the surface of an article onthe belt having a triangular cross section,

apex facing the sliding member. Since each drive member is rotatablycantilevered from one Side of the belt, each arm can be lifted.

The means which lifts the arms is a roller bar associated with each arm.Each roller is free to move up and down directly in front of each arm asit rides over articles which pass beneath it. Each arm has a pair ofprotruding lugs with a lug spaced on each side of the pivot and whichcontact the top of the roller. Thus when the roller is forced upward byan article passing beneath, the associated arm is elevated by the lugsriding on top of the roller. The pressure exerted by the lugs on theroller will cause the roller to tilt with a see-saw motion when thesliding member of each arm is pulled across the surface of an articlehaving a triangular cross section. If the article surface is flat, boththe roller and the sliding member will follow the flat contour of the'article surface.

As the article advances on the belt beneath, the multiple abrasion armswill apply an abrading treatment to the article with the quality ofabrasion determined by the grit or type of sandpaper, emery, polishingmaterial, etc. selected for the abrading member. The types selected canbe mixed for several stages of article surface treatment.

DESCRIPTION OF THE FIGURES FIG. 1 is a perspective partially cut-awayview of the apparatus of the invention.

FIG. 2 is a side cut away view of the apparatus illustrated in FIG. 1.

FIG. 3 is an end sectional view taken along the line 3-3 in thedirection of the arrows in FIG. 2.

FIG. 4 is a partial perspective of the article carrier belt of theapparatus of FIG. 1.

FIG. 5 is a first operational side view of a lifting and tilting meansassociated with the abrasion arms of the apparatus of FIG. 1.

FIG. 6 is a second operational side view continuing the motion shown inFIG. 5.

FIG. 7 is a third operational side view continuing the motion shown inFIG. 6.

FIG. 8 is a fourth operational side view continuing the motion shown inFIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the invention is describedwith reference to abrading machines for de-burring generally fiat andtriangular cross sectional articles such as circuit boards, theapparatus described herein is equally useful for polishing, strippingand surface treating the same articles.

FIG. 1 is a perspective of the upper portion of the article abradingapparatus 11 of the present invention mounted in an enclosing frame 13.An article carrier belt 12 moves in a direction indicated by the arrowover a fiat bed plate 14 which serves as a horizontal belt guide. Anarticle 16, such as a circuit board, is shown on belt 12 passing underfeed roller 18. Stacking plate 15 is set to clear the belt slightly sothat fiat articles may be stacked in front of it and pass underneath oneat a time only. A stacking plate 15 keeps articles stacked withoutfalling, yet allows single articles to pass thereunder. Stacking plate15 can be cantilevered or otherwise secured in position. The contacts 20of feed roller 18 are made of an elastomeric substance which is incontact with belt 12. Flat articles may be stacked in front of the feedroller 18 and stacking plate 15, but only one will pass underneath at atime due to the clearance set beneath plate 15. The feed rollers shouldyield to accommodate articles having triangular cross sections.

The leading edge of article 16 can be seen passing beneath a firstliftable, tiltable abrasion arm 22. If an article has a triangular crosssection, the article is placed on belt 12 so that the triangular sectionhas a base colinear with roller 18 and an apex facing upward.

Each arm 22, 24, etc. includes a lifting means 26 operable in responseto the approach of the article 16 toward the arm 22 as'explained belowas well as in connection with the description of FIGS. 5, 6, 7 and 8.

The lifting means 26 associated with the arms 22, 24, etc. includes. atiltable, liftable roller bar 28 placed on belt 12 under a pair of lugs30, 31. The roller bar 28 is free to roll and be lifted and tilted by anarticle 16 passmg beneath it. The lateral and forward motion of theroller bar 28 is checked by slider blocks 32, 34. The degree of liftprovided to the arms 22, 24, etc. by the lifting means 26 isproportional to the amount that the roller bar 28 is lifted as anarticle passes benath it. By lifting the lugs 30, 3 1 connected to eacharm the lifting means 26 orients each associated arm to the surfaceelevation of an article passing beneath.

The number of arms 22, 24, etc. is selected to provide the amount ofdesired abrasion for the quality and type of surface being treated. Forgenerally flat articles, six arms have been found to provide ampleabrasion but this number is not critical.

Each of the liftable, tiltable arms 22, 24, etc., includes a drve member36, 38, etc. rotatably cantilevered from one end which providesreciprocative motive means. Each drive member is pivotally connected ata pivot 39, 41, etc. to sliding member 40, 42, etc., respectively. Eachpivot 39, 41, etc. is alternately off-center one way, then the other,allowing arms 22, 24, etc. to tilt clockwise and counterclockwise in asee-saw motion about a pivot as the sliding member is pulled across thesurface of an article having a triangular cross section.

Each drive member, e.g. 36, is connected at an end 44 to a rocker bar 46and held down at the opposite end by a spring 45 which controls tensionof each sliding member on the article passing beneath it. The tensiondetermines the amount of abrasion exerted on an article passing beneathit. The tension on all springs is generally set to be equal.

The sliding members, e.g. 40, also include a face portion 48 carrying anabrasion member extending across the belt in a slight interferencerelation to any article on said article carrier belt as explained belowwith reference to the description of FIG. through 8 below. The lugs 30,31 are spaced on opposite sides of the central pivot 39 for lifting thesliding member 40 to which the pivot and lugs are attached. The sliderblocks 32, 34 in which the sliding member 40 rests are made of a lowfriction material such as nylon or Teflon.

In operation the rocker arm 46 rocks back and forth about the shaft 50pushing and pulling drive member end 44 and the connected sliding member40. If an article 16 is under roller bar 28 the height of sliding member40 of the abrasion arm 22 is adjusted by the roller to the properelevation for surface de-burring or polishing or finishing, etc. If thearticle under a roller bar has a triangular cross section the slidingmember will tilt about the pivot with a see-saw motion when it is pulledacross the article surface. The spring tension on each' arm causes thearm to follow the surface contour and tilt when necessary.

The degree of "abrasion provided depends partially on the number ofabrasion arms 22. A multiplicity of arms,

here six, is arranged in'first and second opposed sets with generallyequal numbers of arms in each set having drive members cantilevered fromeither of the opposite sides of the belt. The first set including drivemembers 51, 53 is connected to drive member end 44 and first rocker bar46 through the first driver rod 52, while the second set including drivemembers 54, 56 is connected to another drive member end through thesecond driver rod 58 and second rocker bar 59 for mutually opposedmotion.

Abrading members, e.g. 82 on sliding member 48, maina liquid lubricantthrough sources in a sprinkler pipe 60 mounted Within a fluid shieldjFIG. 2 illustrates the sources 64 in sprinkler pipe 60 in the fluidshield 61 over the first set of drive members 36, 51, 53 and the secondset of drive members 38, 54, 56. The fluid passes onto belt 12 andlubricates articles thereon before falling into the fluid sink 62,whichis a large open tray extending beyond the edges. of belt 12 in ahorizontal plane. 5 u The motivemeans forthe article abrading apparatus11 are first and second motors 64, 66. Motor 64 transmits power to wheel68 through the belt '67; On the oppbsite sides of the rim of wheel 68 ismonted an eccentric power shaft 70 for providing reciprocative power tothefirst and second rocker bars 46, '59 through the drive shafts 71, 72.This provides opposed motion for drive members 36, 51, 53 of the firstset of abrasion arms against the drive members 38, '54, 56 of thesecondset of abrasion arms.

Power transmission is more clearly illustrated in FIG. 3 which showswheel 68 driven by belt 67 and the drive shafts 71, 72 respectivelymounted to the Wheel from the eccentric shaft 70. In operation, rotationof wheel 68 moves the rocker bars 46, 59 in opposite directions therebycausing opposed motion of the drive members 36, 38.

FIG. 3 also illustrates a means for recirculating lubricating fluid fromsink 62 to sprinkler pipe 60 and the sources therein. A drain pipe 77feeds a pump 78 which forces lubricating fluid upwards to the distalextremity of sprinkler pipe 60. As mentioned previously lubricatingfluid falls downward from the sources in pipe 60 toward article carrierbelt 12. Since fluid is recirculated metallic residual particles arekept out of sewer systemsthereby avoiding pollution by the debris fromsurface treating operations. I

FIG. 4 illustrates the detail of belt 12. Cleats 80 are regularly spacedon the surface of belt -12 for frictionally engaging articles placedthereon. To do this thecleats are usually made of rubber or a highfriction elastomer. The cleats are usually more than one quarter inchhigh to allow fluid flow of lubricating fluid between cleats after thefluid has splashed onto the upper side of articles on belt 12. Thespacing between cleats is about a quarter inch or so to permit verysmall circuit boards or-similar articles to be placed on the carrierbelt without slipping. FIGS. 5 through 8 partially illustrate theabrading action of the present apparatus. Belt 12 moves in the directionof the arrow over the flat bed plate 14 carrying a generally rflatarticle 16 to be de-bUrredbThe article may have a horizontal uppersurface or an upper surface tilted with respect to the horizontal. Bedplate 14 should be kept as flat as possible for even abradingoperations.

In FIG. 5 the article 16 is seen to be approaching the feed roller 18.If other articles were stacked on article 16 the feed roller 18 functonsto allow only one article at a time to pass underneath it. The slidingmembers 40, 42 are reciprocating in opposite directions in a plane inand out of the paper on which the figures are drawn at a height slightlyabove, i.e. about a millimeter, the-belt 12. The first and second rollerbars 28, 29-are rotating as the belt moves but are kept from movinglaterallyand forward by slider blocks not shown.

The sliding members 40, 42 each have abrading members 82, 84respectively lining the side of the sliding members facing the belt andthe forwardportion of sliding members in a shape resembling a ski.Slightly resilient pads 86, 88 are interposedbetween abrading members82, 84 and sliding members 40, 42 respectively. 'Ihe abrading membersmay be made of any substance which will carry out the desiredoperation,.i.e. sanding, polishing, de-burring, surface finishing, ,etc.For d e-b urring purposes the abrading. member-is a fine grained emerypaper or sandpaper adhesively secured tothe resilient pads which in turnare adhesively secured to the face of the sliding members. Since the-abrading embers are adhesively secured to the pads, replacement is veryinexpensive and quick compared to prior devices.

The resilient pads 86, 88 yield by temporary compressive deformationwhen in contact with an article 16. The weight of an arm 40, 42 and therespective attached mechanisms including lugs, drive members and thetension exerted by a spring are sufficient to cause the deformation. Theyield of pads 86, 88 provides for long life of the abrading members 82,84 while still achieving good abrading contact. The texture of theabrading members 82, 84 need not be the same but may vary in coursenessto provide a sequence of abrasive textures for any chosen abradingoperation. In general the width of the pads 86, 88 should be kept narrowfor best results with a width of about two inches preferred for bothpads and abrading members. This width preserves uniform abrading action.

In FIG. 6 the article 16 has passed under feed roller 18 and firstroller bar 28 thereby activating the lifting means which includes thelug 31. Lifting of lug 31 by roller bar 28 slightly raises the liftable,tiltable abrasion arm including the sliding member 40. A slightinterference exists between the approaching article 16 and the firstabrading member 82. The second roller bar is still in contact with belt12. The degree of lift and tilt to the lugs by the roller bar is keptsmall or limited by a tension spring to maintain abrading contactbetween the abrading member and an article passing beneath it.

In FIG. 7 article 16 has forced itself beneath the abrading member 82and is undergoing abrasion. The lug 31 is no longer in contact withroller bar 28.

In FIG. 8 article 16 has passed under the second roller bar 29activating a lifting and tilting means which includes lug 33. Tilting ofsliding member 42 would be achieved if article 16 had a tilted surfacewith respect to the horizontal. Note that surfaces with a triangularshape, i.e. an inverted V shaped cross section would be subject tocomplete abrasion since each arm would be pulled over each leg of theinverted V and pivot about the pivot point in a see-saw motion.

In the above operation it has been found optimum to provide a largenumber of transverse abrading strokes to each article for each unit ofbelt travel. For example, about 14 transverse strokes are recommendedfor each inch of belt travel.

Article 16, approaching the second abrading member 84, activates thelifting of the second sliding member 42 with similar abrasion asencountered with the first sliding member 40. In this manner an article16 is de-burred or otherwise treated by the abrading members of thepresent apparatus.

It will be noted that there is virtually no limit on the smallness ofarticles which can be placed on the belt for surface treatment. The onlylimit on largeness is set by the width of the belt.

What is claimed is:

1. An apparatus for abrading flat and triangularly cross sectionalarticles comprising,

an article carrier belt movable over a fixed path,

liftable, tiltable abrasion arms mounted for motion transversely facingthe article carrier belt, said arms each including an abrading memberlining the sides of each arm facing articles moving forward on the belt,

lifting means associated with said abrasion arms for orienting theelevation of each arm above an article on the belt to make abradingcontact with the surfaces of said article under each arm, said liftingmeans operable in response to article approach to said arms, and

motive means for advancing said belt and for moving said arms withtransverse abrading motion.

2. The apparatus of claim 1 where said arms are arranged in first andsecond sets of generally equal numbers for opposed connection to saidmotive means for mutually opposed motion.

3. The apparatus of claim 2 wherein an end of each arm is pivotallyconnected to a rocker bar with the rocker bar of the first set of armsmounted on an opposite side of the article belt from the rocker bar ofthe second set of arms.

4. The apparatus of claim 3 wherein the ends of said rocker barsopposite to said pivotaliy connected ends are joined to drive shafts,the drive shafts associated with the oppositely mounted rocker bars ofthe first and second sets of arms eccentrically connected to the rim ofa wheel driven by said motive means thereby providing opposed motion forsaid first and second sets of arms.

5. The apparatus of claim 3 wherein each of said liftable, tiltable armscomprises,

a drive member rotably cantilevered at one end to said rocker bars andhaving a central pivotal connection, liftable, tiltable sliding memberjoined to said drive member at said pivotal connection for tilting inseesaw motion in response to being pulled over triangular shapedsurfaces, said sliding member having a face portion extending across thebelt and having a pair of lugs disposed on each side of said pivotalconnection, said lugs extending outwardly in the direction of beltmotion, and

an abrading member lining the face portion of the sliding member.

6. The apparatus of claim 5 wherein the lifting means associated withthe arms comprises,

a liftable roller bar placed on said belt under said lugs for liftingsaid lugs when an article is carried on said belt under the roller barwith the degree of lift limited to maintain abrading contact betweensaid abrading member and said article.

7. The apparatus of claim 5 wherein an article on said belt under an armreceives at least ten transverse abrading strokes from an arm during aninch of article travel of said belt.

8. The apparatus of claim 6 wherein the amount of abrading contactmaintained between said article and said abrading member is set by aspring connected at the end of each drive member opposite the end fromwhich said drive member is cantilevered.

9. The apparatus of claim 1 wherein said article carrier belt has spacedsurface cleats for frictionally engaging articles placed thereon and forallowing fluid flow therebetween.

10. The apparatus of claim 1 further defined by an abrading lubricationmeans comprising,

fluid lubricant sources disposed above said belt and colinear therewith,said sources directed downward toward said belt, and

a fluid lubricant sink disposed below said belt and said sources,extending in area beyond the edges of said belt for catching fluidrun-ofl from said belt.

References Cited UNITED STATES PATENTS 888,816 5/1908 Kaeser 51-611,405,639 2/1922 Stuart 5161 3,648,412 3/1972 Hathaway 51-61 FOREIGNPATENTS 96,885 9/1939 Sweden 5161 CHARLES W. LANTHAM, Primary ExaminerG. P. CROSBY, Assistant Examiner

